Denture mounting



June 14, 1938. 2 H, ZA N I 2,120,821

DENTURE MOUNTI NG "Filed Oct. 14, 1935 wfi mz 65 62 64 INVENTOR,

m BY E 3 Patented June 14, 1938 DENTURE MOUNTING Erich H. Zahn, Port Washi to Austenal Laboratories,

a corporation of, New York 1935, Serial No. 44,868

Application October 14,

I 5 Claims.

My present invention relates generally to dentures, and has particular reference to certain improvements relative to the mounting of denture facings to a backing.

While I have herein illustrated and shall hercinafter described the invention in connection with a partial removable denture, nevertheless it will be understood that the invention is equally applicable to other well known types of appliances wherein a base or backing, composed of metal or other denture material, is associated with a facing -or facings of porcelain or the like, simulating teeth.

It has been customary practice in mounting a porcelain facing or the like to a denture backing, to provide the facing on its rear surface with an undercut recess or groove which is adapted to be slid longitudinally onto a complementary retention rib that is carried by the backing. For a number of reasons, well known to those conversant with the art, the longitudinal or endwise application of such a facing is not always efficient or desirable, and it is far more advantageous to be able to apply a facing to a backing in a flatwise or broadside manner.

Various attempts have heretofore been made to accomplish this object, but one of the problems which has not heretofore been successfully overcome is the matter of securing the facing to the backing in an efficient and firm manner.

It is a general object of my present invention to provide a denture mounting wherein a tooth facing having an undercut recess in its rear surface is adapted to be associated with a backing in a manner whereby the facing may be applied laterally, i. e., fiatwise, and whereby an unusually simple and highly efficient means is provided for securing the facing in place.

Briefly, my invention resides in the provision of a backing having a retention rib whose end, i. e., its outer edge portion, is narrow enough to permit the rib topass through the narrow portion of the undercut recess in the facing; together with an additional and specially constructed and configured key or insert element which, in a preferred embodiment, is insertable endwise into the recess alongside of the rib. The key of the present invention is of such a configuration that it provides, with the rib end, sufiicient cross sectional area to snugly fill the recess.

I am aware of attempts that have heretofore been made to accomplish this same general purpose by the enclwlse insertion of a wedge'element which deforms or deflects a rib provided-on the backing. However, such a constructionrequires (ill. 32-9) the application of force ngton, N. Y., assignor Inc., New York, N. Y.,

and the provision of a rib of deflectable material, and is beset with the serious danger of splitting or injuring the facing.

In accordance with my present invention, the

retention rib that is provided on the backing is of the same general rigid character which is customarily employed, the rib being of unyielding material, the main difference from the conventional rib lying in the may be said to be und cess which it enters. or insert element is throughout, and does n merely as a space-filling element.

fact that the present rib crsized" relative to the re- Moreover, the present key of uniform cross-section 0t function as a wedge but The present key has a cross-sectional configuration whereby one portion conforms to the contour of at least one part of the recess, forms to rib end. In a sense, figuration which mentary to that of the is unaccompanied by formation, or likelihoo Preferably, length of an elongated conforms to the present key while another portion conthe contour of at least one part of the the present key has a conand is complerib, whereby its insertion any undue stresses, ded of damage.

comprises a selected element having a uniform cross-sectional configuration and area throughout its length and being of frangible material.

I achieve the foregoing objects, and such other objects as may hereina fter appear or be pointed out, in the manner illustratively exemplified in the accompanying drawing, wherein- Figure 1 is denture constructed in a f ront'elevational view of a partial accordance with the present invention and shown in association with the teeth which it augments;

Figure 2 is a cross-sectional line 2-2 of Figure l, with stant'ially along the view taken subcertain elements shown in exploded relation;

Figure 3 is a fragmentary perspective view showing the present backing,

the facing, and the key, in exploded relation;

Figure 4 is an enlarge through the assembly and Figures 5-12. are views similar to Figure d cross-sectional view of facing and backing;

showing various modifications.

I have chosen to illustrate a denture which comprises the backing 2|], with flattened outer faces 2% adapted to facings 22, side by si illustrating one of the construction, I have vided with the oppo The backing may such as metal; and th be of any suitable mate iaaccommodate two tooth. de. For the purpose of advantages of the present shown the denture prosite clamps 23 and M.

e retention rib of Figures 1-4 consists of the projection 25 which, as indicated most clearly in Figure 4, consists of the shank portion 26 and the relatively enlarged end or head 21. This retention rib is of rigid unyielding material, and in the preferred em bodiment the end or head 2! is of substantially circular cross-sectional configuration, as indicated in Figure 4. The rib does not extend for the full length of the backing, but terminates short of the outer end of the backing, as shown in Figure 3.

The facing 28, which may be of porcelain or other suitable material, is provided with the fiattened rear surface 29 adapted to contact. with the flattened surface 2|.- In the rear surface there is provided the usual undercut recess 30, and by the term undercut I refer to a recess whose cross-sectional configuration is like that of a keyhole or T-shaped, i. e., a recess whose inner portion is relatively wide while its outer portion is relatively narrow. The recess extends from the rear end or surface 3| to a point short of the outer tip of the facing, as shown most clearly'in Figure 3.

In conventional practice, the recess 30 is accurately conformed in cross-section to that of the retention rib, whereby the facing must be applied to the backing by sliding it endwise into position. In accordance with my present invention, the parts are so proportioned that the head or end 2'! of the rib may pass freely through the narrow portion of the recess. This permits the facing to be applied flatwise against the backing. In accordance with my invention, the unoccupied space within the recess is filled by the use of an added key element.

The key 32 is, in the embodiment of Figures 1-4, of substantially tubular cross-sectional configuration, or it may be said to be C-shaped,

adapting it to an enveloping relationship to the rib end 21.

The key is purposely of a configuration and,

size which conforms one portion, its outer surface 33,' to the recess 30, and which conforms another portion, i. e., its inner surface 34, to the contour of at least one part of the 'rib end 21. The key preferably forms a selected length of an elongated element of substantially uniform cross-section and area throughout its length. In practice, the end of such elongated element is slid endwise into the recess after the facing has been applied to the backing. The selected length is then cut off or broken off, leaving the parts in the rigidly associated relationship of Figure 4. The term frangible as used herein, with respect to a key element of this type, is intended to signify the susceptibility to a feasible cutting or breaking of this character.

The key element is, however, not necessarily a cut or broken length of a longer piece. It may be formed in situ, under certain circumstances, by forming it of hardenable plastic material.

It will be noted that the secure assembly is accomplished without any Wedging action, without subjecting the facing to any dangerous stresses, and Without necessitating any precarious or forceful deformation of the retention rib. Cement is, of course, applied as required during the assembly of the parts.

One of the advantages of the present construction is clearly illustrated in Figure 3, wherein it will be observed that the inner end of the clasp 24 intrudes upon the surface 2i of the ing, in the ordinary manner, could not be ac- In Figure 5, the backing 36 is provided with a rib 3'! whose end 38 has the opposed lateral grooveways 39 formed therein. The facing 40 has the undercut recess 4|; and the key consists of the two rod-shaped portions 42 which fit snugly within the grooveways 39. The key may be said to have a cross-sectional configuration whereby one portion is adapted to nest within the lateral grooveway in the rib.

In Figure 6, the rib 43 has an end 44 of U- shaped cross-section. The axis of the U is substantially transverse to the axis of the rib, whereby a lateral grooveway 45 is provided. The key 46 is in this instance of a cross-sectional configuration whereby one portion, i. e., the surface 41, conforms to the recess in the facing 48, while another portion, i. e., the inner surface conforms to and fits snugly within the grooveway 45.

The construction of Figure 7 is similar to that of Figure 4, the rib having a relatively narrow shank portion 49 and an enlarged rounded head or end 50. In this case, the key 5| has its outer part C-shaped, so that it envelops the rib end 50; and this construction differs from that of Figure 4 only in the provision of extensions 52 on the arms of the C, so that the space on opposite sides of the shank 49 is filled.

In Figure 8, the rib 53 is similar to that shown in Figure 6, a U-shaped end 54 providing a lateral grooveway. The key 55 is of substantially circular cross-section, conforming it to a snug fit with the grooveway, i. e., with the U-shaped end 54. The construction of Figure 8 differs from that of Figure 6 in that the key does not conform to any portion of the rib end except the concave surface of the U-shaped end 54.

In Figure 9, the rib has a shank 56 and an enlarged end 51 which is of substantially halfround cross-sectional configuration. The key 58 has a complementary substantially half-round cross-sectionalconfiguration, the flat surface of the key and the flat surface of the rib fitting snugly against each other.

The rib 59 of Figure 10 has a U-shaped end 60 similar to that of Figures 6 and 8, but the concave surface of the U is of angular character, adapting it to snugly receive a key 6| having a crosssection conforming to a sector of a circle.

In Figure 11, the rib 62 is similar to'that shown in Figure 4, and has an enlarged rounded head 63. The key, instead of completely enveloping the end 63 of the rib, has a U-shaped portion 64 which only partially envelops the rib end. The key also has a relatively straight portion 65 which fits snugly alongside of the shank of the rib.

In Figure 12, the rib 66 has an enlarged end 61 differing from that of Figures 4, '7, and 11 in that the end is not completely rounded. The rib of Figure 12 is more T-shaped in cross-section. The key 68 is substantially C-shaped, adapting it to an enveloping relationship to the enlarged rib end El; and the configuration of the key conforms to that of the end 61.

Other modifications will readily suggest themselves to those skilled in the art, the character-la: ing feature of the present invention lying in the relationship of rib end to recess, whereby the rib end may pass freely through the narrower portion of the recess, and whereby the added key insert is a space-filling element which provides, in conjunction with the rib, sufficient cross-sectional area to snugly fill the ,recess and thereby hold the face firmly to the backing.

In general, it will be understood that changes in the details, herein described and illustrated for the purpose of explaining the nature of my invention, may be made by those skilled in the art without departing from the spirit and scope of the invention as expressed in the appended claims. It is, therefore, intended that these details be interpreted as illustrative, andnot in a limiting sense.

Having thus described my invention, and illustrated its use, what I claim as new and desire to secure by Letters Patent is- 1. In a denture, a backing having a longitudinal, rigid retention rib of keyhole cross-section, a facing having a complementary recess of corresponding cross-section, the wider part of the rib being narrower than the narrow part of said recess so that the facing may be applied broadside to the backing with the rib accommodated in said recess, and a tubular key insertable endwise over the wider part of said rib and adapted to snugly occupy the annular space betweenthe rib and the wall of therecess, uniform cross-section throughout its length.

2. In a denture, a facing having a longitudinal recess of keyhole cross-section, said recess extending to the cervical end of said facing, a backing having a longitudinal rigid retention rib, said rib having an enlarged outer edge portion which is nevertheless narrower than the narrow part of said recess, whereby the facing may be applied broadside to the backing with the rib accommodated in said recess, and a key insertable end-.

wise into said recess and adapted snugly to cocupy at least a portion of the space between the rib and the recess well, said key being of uniform cross-section throughout its length and having a cross-sectional configuration whereby one portion conforms to the contour of at least one part of the recess and another portion conforms to at least one part of the enlarged rib edge.

said key being of 3. In a denture, a facing having a longitudinal recess of keyhole cross-section, said recess extending to the cervical end of said. facing, a backing having a longitudinal rigid retention rib, said rib having an enlarged outer edge portion which is nevertheless narrower than the narrow part of said recess, whereby the facing may be applied broadside to the backing with the rib accom modated in said recess, and a key insertable endwise into said recess and adapted snugly to occupy at least a portion of the space between the rib and the recess wall, said key being of uniform cross-section throughout its length and having a cross-sectional configuration of which at least a part is (iv-shaped, adapting said part to an enveloping relationship to said enlarged rib edge.

4. In a denture, a facing having a longitudinal recess of substantially keyhole cross-section, said recess extending to the cervical end of said facing, a backing having a longitudinal rigid retention rib, said rib having an enlarged outer edge portion which is nevertheless narrower than the narrow part of said -recess, whereby the facing may be applied broadside to the backing with the rib accommodated in said recess, and whereby a space. is formed between the rib and the recess, said space being of uniform cross-section, and an elongated key insertable endwise into said space and so dimensioned and contoured that it will engage the walls of said recess and rib at a number of points sufficient to lock said facing firmlyto said backing.

5. In a denture, a facing having a longitudinal recess of substantially keyhole cross-section, said recess extending to the cervical end of said facing, a backing having a longitudinal rigid retention rib, said rib having an enlarged outer edge portion which is nevertheless narrower than the narrow part of said recess, whereby the facing may be applied broadside to the backing with the rib accommodated in said recess, and whereby a space is formed betweenthe rib and the recess, said space being of uniform cross section, and an elongated key of substantially uniform crosssection insertable endwise into said space and so dimensioned and contoured that it will engage the walls of said recessand ribat a number of points suiiicient to lock said facing firmly to said backing.

' ERICK H. ZAHN. 

